
import 'package:test/test.dart';

void main() {
  test('calculate', () {
    final a = <int>{1,3};
    final b = <int>{2,3,4};
    final c = <int>{2,4};
    final d = <int>{3,4};
    final value = a.difference(b.union(c).union(d)).toList();
    print(value);
    expect(value.length == 1, isTrue);
    expect(value.first == 1, isTrue);
  });


}
